Nowadays, there are two main kinds of freight car bogies in the word, one is three-piece casting steel bogie, and the other one is fabricated bogie.
The three-piece casting steel bogie comprises side frames, bolster and wheel set assemblies, and further comprises brake rigging and spring damping device. Connection between two side frames of a three-piece casting steel bogie in a horizontal plane relies on a load spring, a bolster, a side frame pedestal, and a journal box including adaptor and bearing. FIG. 1 is a schematic structural view of a freight car bogie in the prior art. As shown in FIG. 1, two side frames 1 are built over a wheel set assembly 2 through the side frame pedestal and the journal box, the two side frames 1 are connected with each other by a bolster 5, a freight car bogie 100 has loose connections and warp resistant rigidities of two side frames 1 are low. When a vehicle runs fast, wheel sets are excited due to various irregularities of the track, so that warp displacement occurs easily between the two side frames 1. Again referring to FIG. 1, a distance d is generated between the two side frames 1 at front side to rear side, resulting in hunting movement of the freight car, so that wheel flanges are seriously worn and derailment possibility increases. A situation of warp deformation of the freight car bogie 100 is as shown in FIG. 1.
Additionally, the wheel sets are connected and positioned through contact between the adaptor and side frame pedestal roof, which is a steel-steel friction pair, a type of dry friction constraint. A dry friction form between the adaptor and the side frame pedestal roof causes a large difference of friction forces between an empty car and a loaded car. For the empty car, the control force to the wheel sets applied by the side frame through adaptor is weak, the wheel sets inclines to rotary about the vertical shaft, but for the loaded car, the control force to the wheel sets applied by the side frame through adaptor is strong, the wheel sets is hard to rotary about the vertical shaft. When the vehicle passes along a curve line, angles of attack of the wheel flanges between the wheel sets and the track are large upon the empty car or the loaded car, so that tendency to radial positions and automatic reset are unable to be realized, causing problems such as more serious wheel flange wear and abrasion between the adaptor and the side frames.
Further, clearance side bearing structures are used at two sides on the top of the bolster. The track structures are unable to provide the car body with a rotation suppression effect for stability of the bogie, so that reliability of operation of the vehicle is decreased.
Moreover, channel steel brake beam structures are adopted at two sides of the side surfaces of the bolster. The channel steel brake beam is a welded structure, which has potential safety hazards and high maintenance cost.
The above technical defects of the freight car bogie affect performance of the freight car bogie during operation along a tangent line and a curve line to different degree, reduce an operation speed and stability of the freight car, and increase operation cost and maintenance cost.